Global constraints from RHIC and LHC on transport properties of QCD fluids in CUJET/CIBJET framework

We report results of a comprehensive global х~2 analysis of nuclear collision data from RHIC(0.2 ATeV),LHC1(2.76 ATeV), and recent LHC2(5.02 ATeV) energies using the updated CUJET framework. The framework consistently combines viscous hydrodynamic fields predicted by VISHNU2+1(validated with soft p_T﹤2 GeV bulk observables) and the DGLV theory of jet elastic and inelastic energy loss generalized to QGP fluids with an sQGMP color structure, including effective semi-QGP color electric quark and gluon as well as emergent color magnetic monopole degrees of freedom constrained by lattice QCD data. We vary the two control parameters of the model(the maximum value of the running QCD coupling, c, and the ratio cm of color magnetic to electric screening scales) and calculate the global х~2(α_c,c_m) compared with available jet fragment observables( R_(AA),v_2). A global х~2 minimum is found with α_c≈0.9±0.1 and c_m≈0.25±0.03. Using CIBJET, the event-by-event(ebe) generalization of the CUJET framework, we show that ebe fluctuations in the initial conditions do not significantly alter our conclusions(except for v_3). An important theoretical advantage of the CUJET and CIBJET frameworks is not only its global х~2 consistency with jet fragment observables at RHIC and LHC and with non-perturbative lattice QCD data, but also its internal consistency of the constrained jet transport coefficient, ■(E,T)/T~3, with the near-perfect fluid viscosity to entropy ratio(η/s～T~3/■～0.1-0.2) property of QCD fluids near Tc needed to account for the low p_T﹤2 GeV flow observables. Predictions for future tests at LHC with 5.44 ATeV Xe + Xe and 5.02 ATeV Pb + Pb are also presented.     

Quantifying the chiral magnetic effect from anomalous-viscous fluid dynamics

The Chiral Magnetic Effect(CME) is a macroscopic manifestation of fundamental chiral anomaly in a many-body system of chiral fermions, and emerges as an anomalous transport current in the fluid dynamics framework. Experimental observation of the CME is of great interest and has been reported in Dirac and Weyl semimetals. Significant efforts have also been made to look for the CME in heavy ion collisions. Critically needed for such a search is the theoretical prediction for the CME signal. In this paper we report a first quantitative modeling framework, Anomalous Viscous Fluid Dynamics(AVFD), which computes the evolution of fermion currents on top of realistic bulk evolution in heavy ion collisions and simultaneously accounts for both anomalous and normal viscous transport effects. AVFD allows a quantitative understanding of the generation and evolution of CME-induced charge separation during the hydrodynamic stage, as well as its dependence on theoretical ingredients. With reasonable estimates of key parameters, the AVFD simulations provide the first phenomenologically successful explanation of the measured signal in 200 AGe V Au Au collisions.     

Investigation of experimental observables in search of the chiral magnetic effect in heavy-ion collisions in the STAR experiment

The chiral magnetic effect(CME)is a novel transport phenomenon,arising from the interplay between quantum anomalies and strong magnetic fields in chiral systems.In high-energy nuclear collisions,the CME may survive the expansion of the quark-gluon plasma fireball and be detected in experiments.Over the past two decades,experimental searches for the CME have attracted extensive interest at the Relativistic Heavy Ion Collider(RHIC)and the Large Hadron Collider(LHC).The main goal of this study is to investigate three pertinent experimental approaches:the$\gamma$correlator,the R correlator,and the signed balance functions.We exploit simple Monte Carlo simulations and a realistic event generator(EBE-AVFD)to verify the equivalence of the core components among these methods and to ascertain their sensitivities to the CME signal and the background contributions for the isobar collisions at the RHIC.